DESCRIPTION (Applicant's abstract): Substance use disorder (SUD) is the most common and clinically important comorbid condition among individuals with severe mental illness. SUD has been implicated in many negative outcomes, e.g., relapse, depression, hospitalization, homelessness, incarceration, victimization, and infection with human immunodeficiency virus. New programs that integrate mental health and substance abuse services for these dually diagnosed individuals are effective over the short run, but we have little information about long-term outcomes in real-world settings. The proposed project will extend the Connecticut Dual Diagnosis Study of 187 adults with dual disorders in Hartford and Bridgeport, CT, who have been studied already for three to five years in an integrated treatment system. Extending the follow-up to 8-10 years will yield critical information on the pattern, stability, prediction, timing, and correlates of remissions of substance use disorder in this population. Further, it will be conducted in parallel with and using the same methods as a 10-year follow-up study of dually diagnosed patients in rural New Hampshire. The long-term data will allow us to chart the course of abstinence, asymptomatic use, remission, and recovery in dual-diagnosis patients. The study will increase our understanding of the relationships among substance disorder, clinical outcomes, and service costs over time. Longitudinal data will also allow us to examine several hypotheses from the literature regarding the effects of treatment and non-treatment experiences, such as the use of new medications and participation in self-help, on the course of SUD in this population. Finally, we will take maximal advantage of conducting the rural and urban studies in conjunction with one another.